The function*
keyword can be used to define a generator function inside an expression.
You can also define generator functions using the function*
declaration.
The function*
keyword can be used to define a generator function inside an expression.
You can also define generator functions using the function*
declaration.
function* (param0) { statements } function* (param0, param1) { statements } function* (param0, param1, /* …, */ paramN) { statements } function* name(param0) { statements } function* name(param0, param1) { statements } function* name(param0, param1, /* …, */ paramN) { statements }
Note: An expression statement cannot begin with the keyword function
to avoid ambiguity with a function*
declaration. The function
keyword only begins an expression when it appears in a context that cannot accept statements.
name
Optional
The function name. Can be omitted, in which case the function is anonymous. The name is only local to the function body.
paramN
Optional
The name of a formal parameter for the function. For the parameters' syntax, see the Functions reference.
statements
Optional
The statements which comprise the body of the function.
A function*
expression is very similar to, and has almost the same syntax as, a function*
declaration. The main difference between a function*
expression and a function*
declaration is the function name, which can be omitted in function*
expressions to create anonymous functions. A function*
expression can be used as an IIFE (Immediately Invoked Function Expression) which runs as soon as it is defined, allowing you to create an ad-hoc iterable iterator object. See also the chapter about functions for more information.
The following example defines an unnamed generator function and assigns it to x
. The function yields the square of its argument:
const x = function* (y) { yield y * y; };
Desktop | Mobile | Server | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Opera | Safari | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | WebView Android | Deno | Node.js | ||
function* |
49 | 12 | 26 | 36 | 10 | 49 | 26 | 36 | 10 | 5.0 | 49 | 1.0 | 4.0.0 | |
trailing_comma |
58 | 79 | 52 | 45 | 10 | 58 | 52 | 43 | 10 | 7.0 | 58 | 1.0 | 8.0.0 |
© 2005–2023 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/function*